I started with Papazian's "The New Complete Joy of Home Brewing" I got off Amazon used for a buck, but it was from a printing in the early 80s and a lot has changed since then. He has several newer versions, on of which I looked at at the library and it was really nice.

I also like Papazian's "Homebrewer's Companion" This is more of a supplement to "The complete joy of homebrewing" but it still has some good info and a lot of great recipes. Also, if you are into gardening, "The Homebrewer's Garden" is a really great book.